Glassnijder (Brachytron pratense) en Smaragdlibel (Cordulia aenea) als waterkwaliteitsindicatoren

Van de Haterd, R.J.W., 2004. Brachytron pratense and Cordulia aenea as water quality indicators. Brachytron 8(1): 9-14. Brachytron pratense and Cordulia aenea are often regarded as indicators of a relatively good water quality. The article presents the results of a study of the odonate fauna and the water quality of 31 eutrophic water bodies in the south-eastern part of The Netherlands. Localities with or without Cordulia aenea differed significantly in water quality, waters with or without Brachytron pratense did not. However, it is suggested that both Brachytron pratense and Cordulia aenea do prefer relatively clear waters (over 0,4 m secchi-depth) with a low electric conductivity (below 400 μS/cm). The data also suggest a combined effect: both species are more critical to clearness in water bodies with a higher conductivity. Because conductivity and clearness can be measured without laboratory facilities, the method used provides a way to relate the odonata fauna to the water quality at a relatively low cost.